Liquid crystal display

Abstract

In a liquid crystal display using a liquid crystal exhibiting a smectic phase, a display of good quality is accomplished by alleviating the burn-in phenomenon caused by its layer structure or by an internal electric field induced by spontaneous polarization. To achieve this, the liquid crystal display is equipped with a display data conversion circuit which forcibly sets an arbitrary pixel into a prescribed display state for a prescribed period regardless of the display data to be written to the pixel, thereby correcting the change of its layer structure and preventing the internal electric field due to the spontaneous polarization occurring in the same direction from lasting for too long a period.

What is claimed is:  
     
       1. A liquid crystal display containing a plurality of pixels arranged in a matrix pattern and having, between a pair of substrates, a liquid crystal exhibiting a smectic phase, comprising: 
       a circuit for generating display data to write to said pixels;  
       a circuit for receiving said display data from said display data generating circuit, and for generating a scanning voltage and a signal voltage to be applied to said pixels; and  
       a display data conversion circuit for converting said display data in order to forcibly set random pixels of the plurality of pixels in a prescribed display state for a prescribed period regardless of said display data, the random pixels being distributed throughout the matrix pattern.  
     
     
       2. A liquid crystal display containing a plurality of pixels arranged in a matrix pattern and having, between a pair of substrates, a liquid crystal exhibiting a smectic phase, said substrates having a plurality of scanning electrodes and signal electrodes, respectively, said liquid crystal display comprising: 
       a display data generating circuit for generating display data to write to said pixels;  
       a scanning voltage generating circuit for generating, based on said display data from said display data generating circuit, a scanning voltage to be applied to said scanning electrodes;  
       a signal voltage generating circuit for generating, based on said display data from said display data generating circuit, a signal voltage to be applied to said signal electrodes; and  
       a display data conversion circuit for converting said display data in order to forcibly set random pixels of the plurality of pixels in a prescribed display state for a prescribed period regardless of said display data, the random pixels being distributed throughout the matrix pattern.  
     
     
       3. A liquid crystal display according to claim  1  or  2 , wherein said display data conversion circuit is provided between said display data generating circuit and said signal voltage generating circuit. 
     
     
       4. A liquid crystal display according to claim  1  or  2 , wherein said display data conversion circuit has a function to designate a pixel whose display data is to be converted. 
     
     
       5. A liquid crystal display according to claim  1  or  2 , wherein said display data conversion circuit has a function to randomly select a pixel whose display data is to be converted. 
     
     
       6. A liquid crystal display according to claim  1  or  2 , wherein said display data conversion circuit has a function to set the interval at which said display data is converted to an arbitrary value. 
     
     
       7. A liquid crystal display according to claim  1  or  2 , wherein said display data conversion circuit has a function to automatically change the interval at which said display data is converted. 
     
     
       8. A liquid crystal display according to claim  1  or  2 , wherein said display data conversion circuit has a function to arbitrarily set the number of pixels per scanning line whose display data is to be converted forcefully. 
     
     
       9. A liquid crystal display according to claim  1  or  2 , wherein said display data conversion circuit has a function to automatically change the number of pixels per scanning line whose display data is to be converted forcibly. 
     
     
       10. A liquid crystal display according to claim  1  or  2 , wherein said display data conversion circuit has a function to set the level of said prescribed display state, to which said conversion is to be made, to an arbitrary level. 
     
     
       11. A liquid crystal display according to claim  1  or  2 , wherein said display data conversion circuit has a function to automatically change the level of said prescribed display state to which said conversion is to be made. 
     
     
       12. A liquid crystal display according to claim  1  or  2 , wherein said liquid crystal exhibiting a smectic phase is a ferroelectric liquid crystal or an antiferroelectric liquid crystal.